JP2006268908A - Optical information recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording/reproducing device capable of achieving a stable tracking control operation by reducing the amplitude and the offset fluctuation of a tracking error signal with respect to the target recording layer of a multilayer recording medium. <P>SOLUTION: This device is provided with an own layer recorded state detection circuit 14 for detecting a recorded state in the information track of a recording layer of a focused optical spot, and an other layer recorded state detection circuit 19 for detecting a recorded state in the information track of a recording layer other than the recording layer of the focused optical spot. The amplitude and the offset of a tracking error signal are corrected according to the own layer recorded state detected by the own layer recorded state detection circuit and the other layer recorded state detected by the other layer recorded state detection circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information recording / reproducing apparatus for recording or reproducing information on an optical disc having a plurality of recording layers using a converged light spot.

  DVD-R, DVD-RAM, and the like are known as optical recording media capable of optically recording or reproducing information. Information is recorded or reproduced by irradiating an optical recording medium with a laser beam such as a semiconductor laser as a light source and irradiating a light beam that is finely condensed through a lens.

  In these optical recording media, technical development for further increasing the recording capacity has been actively conducted. Among these, the multilayer recording medium in which the information layers are laminated has a feature that the recording capacity can be increased according to the number of information layers, and that it can be easily combined with other high-density recording techniques. As a multi-layer recording medium, a read-only DVD-ROM disk has already been put into practical use, and a recordable multi-layer in which recordable information layers such as a phase change material and a dye material such as DVD-R and DVD-RAM are laminated. Recording media are also being put into practical use.

  In an optical information recording / reproducing apparatus typified by a DVD-R device or a DVD-RAM device, information recording is performed by irradiating a light spot having a diameter of about 0.5 μm to an information track having a pitch of about 0.74 μm provided on a disk. Playback is performed. When irradiating a disc surface with a light spot, focus control is performed to follow the vertical direction with an accuracy of about ± 0.5 μm, and tracking control is performed so that the track deviation between the information track and the light spot follows with an accuracy of about ± 0.1 μm. Done.

  These servo operations are performed based on a control signal obtained by receiving reflected light from the optical recording medium by a photodetector. Information recording or reproduction is performed on an optical recording medium using a phase change material or a dye material for an information layer by using a change in the amount of reflected light of light irradiated on the information layer thin film. In recording information, the optical recording medium is irradiated with light having a power about 10 times higher than that during reproduction. Therefore, the photodetector for obtaining signals for servo operation (focus error signal, tracking error signal) has an objective lens on the condition that the reproduction track state is unrecorded or recorded and the operation is reproduction or recording. Even if the operation of following the position of the information layer thin film is the same, the amount of reflected light changes, so the amplitude of the servo signal (focus servo signal, tracking servo signal) changes.

  To compensate for the change in servo signal amplitude due to the difference in power applied to the optical recording medium during recording and playback, the focus control circuit gain is inversely proportional to the value of the sum signal of the focus error signal during the focus operation. In the tracking operation, the gain of the tracking control circuit is made inversely proportional to the value of the sum signal of the tracking error signal, and correction is performed so that the amplitude of the servo signal becomes constant even when the power of the light spot changes.

  A conventional optical information recording / reproducing apparatus will be described below with reference to FIG. FIG. 4 is a block diagram showing a configuration example of a conventional optical information recording / reproducing apparatus.

  In FIG. 4, the disk 3 has two recording layers (first recording layer 1 and second recording layer 2) on which information is recorded along spiral or concentric tracks, not shown. It is configured to rotate by a spindle motor. Recording and reproduction with respect to each recording layer of the disk 3 are performed by the optical pickup 4. A semiconductor laser (LD) 5, a collimator lens 6, a beam splitter 7, an objective lens 8, and a two-divided photodetector (PD) 9 are attached to the optical pickup 4.

  The tracking error detection circuit 10 obtains the difference and sum of the output signals of each of the two-divided PD 9 (PD9 (a), 9 (b)), and removes high-frequency components unnecessary for control through the LPFs 11 and 12, respectively. The dividing circuit 13 divides the output signal LOD of the LPF 11 by the output signal LOA of the LPF 12 and outputs the result as a tracking error signal TE that is a displacement amount from the center of the information track on each recording layer.

  Next, a specific operation when recording and reproduction is performed on the information track on the first recording layer 1 will be described with reference to FIG.

  The light beam emitted from the semiconductor laser 5 becomes parallel light by the collimator lens 6, and is condensed on the information track on the first recording layer 1 via the beam splitter 7 and the objective lens 8. Using a part of the reflected light from the disk 3, the objective lens 8 is moved in the vertical direction so that the focal position of the light beam focused by the objective lens 8 always matches the first recording layer 1 on the disk 3. Focus control is being performed.

  A part of the reflected light from the disk 3 enters the two-divided PD 9 via the objective lens 8 and the beam splitter 7, and the two-divided PD 9 indicates the amount of light detected by each PD 9 (a) and 9 (b). Output voltage.

The tracking error detection circuit 10 obtains the difference and sum of the output signals of the PDs 9 (a) and 9 (b) of the two-divided PD 9, and removes the high frequency components unnecessary for control through the LPFs 11 and 12, respectively. The circuit 13 divides the output signal LOD of the LPF 11 by the output signal LOA of the LPF 12 and outputs it as a tracking error signal TE that is a radial displacement amount from the center of the information track on each recording layer. Tracking control for moving the objective lens 8 in the radial direction of the disk 3 is performed so that the level of the tracking error signal TE becomes zero.
JP 2001-93189 A JP 2000-306252 A

  However, in a multilayer recording medium composed of a plurality of recording layers, a light detector for detecting a servo signal (focus servo signal, tracking servo signal) using reflected light from not only the target recording layer but also an adjacent recording layer Incident on the servo signal, which causes a change in amplitude or offset in the servo signal. This problem will be described with reference to FIG.

  FIG. 5 shows various parts of the conventional optical information recording / reproducing apparatus shown in FIG. 4 when the position of the objective lens 8 with respect to the disk 3 is changed when information is reproduced from the first recording layer 1 of the disk 3. It is a wave form diagram of a signal.

  In FIG. 5, RL1 (a) is the amount of reflected light from the first recording layer 1 to the PD 9 (a), RL1 (b) is the amount of reflected light from the first recording layer 1 to the PD 9 (b), and RL2 ( a) is the amount of reflected light from the second recording layer 2 to the PD 9 (a), RL 2 (b) is the amount of reflected light from the second recording layer 2 to the two-divided PD 9 (b), and LOD passes through the LPF 11. The difference signal between the output signal of PD9 (a) after output and the output signal of PD9 (b), LOA, is the addition of the output signal of PD9 (a) and the output signal of PD (b) after passing through the LPF 12 A signal and TE indicate a tracking error signal after passing through the divider circuit 13.

  Further, in the disc 3, the area X1 is in a state where the first recording layer 1 is not recorded and the second recording layer 2 is not recorded, and the area X2 is the second recording where the first recording layer 1 is not recorded. Layer 2 is in a recorded state, area X3 is in a state where the first recording layer 1 has been recorded and the second recording layer 2 is also in a recorded state, and area X4 is in a state where the first recording layer has been recorded and the second recording layer 2 is recorded. The recording layer is in an unrecorded state. Hereinafter, problems in each region in such a state will be described.

(Region X1)
Since the light spot is focused on the first recording layer 1, almost the same amount of reflected light is incident on PD 9 (a) and PD 9 (b), and the light from the first recording layer 1 is incident. The reflected light amount RL1 (a) to the PD 9 (a) is diffracted by the track on the first recording layer 1 and shows a sinusoidal change.

  Similarly, the reflected light amount RL1 (b) from the first recording layer 1 to the PD 9 (b) also shows a sinusoidal change, but the sine wave change due to diffraction is opposite in phase to RL1 (a).

  On the other hand, since the light spot is not focused on the second recording layer 2, the reflected light is unevenly incident on the PD 9 (a) and the PD 9 (b) (for example, a ratio of 2: 1). In addition, the influence of diffraction by the information track on the second recording layer 2 is very small. Thereby, the reflected light amount RL2 (a) from the second recording layer 2 to the PD 9 (a) and the reflected light amount RL2 (b) from the second recording layer 2 to the PD 9 (b) are respectively illustrated. Becomes unequal.

  The differential signal LOD that is the output signal of the LPF 11 has a signal waveform proportional to (RL1 (a) + RL2 (a)) − ((RL1 (b) + RL2 (b)). The signal LOA has a signal waveform proportional to (RL1 (a) + RL2 (a)) + ((RL1 (b) + RL2 (b)).

  The tracking error signal TE after passing through the divider circuit 13 has a waveform as shown. That is, the tracking error signal TE has an offset proportional to the non-uniform amount of reflected light from the second recording layer 2 to the PD 9 (a) and PD 9 (b).

(Region X2)
The amount of light reflected from the first recording layer 1 to the PD 9 (a) and PD 9 (b) is the same, but the reflected light from the second recording layer 2 records information in the second recording layer 2. Therefore, the reflectance at the recorded track is lowered (for example, 1/2). That is, the reflected light amount RL1 (a) from the first recording layer 1 to the PD 9 (a) and the reflected light amount RL1 (b) from the first recording layer 1 to the PD 9 (b) are the same as those in the region X1. However, the reflected light amount RL2 (a) from the second recording layer 2 to the PD 9 (a) and the reflected light amount RL2 (b) from the second recording layer 2 to the PD 9 (b) are respectively shown in the figure. As shown, it becomes smaller in proportion to the decrease in the reflectance than those in the region X1.

  As a result, the amount of offset generated in the tracking error signal TE due to unevenness in the amount of reflected light from the second recording layer 2 to the PD 9 (a) and PD 9 (b) is also reduced. Further, the addition signal LOA, which is the output signal of the LPF 12, decreases, and the amplitude of the tracking error signal TE increases in inverse proportion thereto.

(Region X3)
Information is recorded on the first recording layer 1, and the reflectance decreases in the recorded track, and the recorded data (high-band light / dark change) itself is also detected by the two-segment PD 9. Therefore, the reflected light amount RL1 (a) from the first recording layer 1 to the PD 9 (a) and the reflected light amount RL1 (b) to the PD 9 (b) are reduced as a whole as shown in the figure. The level is lowered, and a waveform in which high-frequency components due to leakage of recorded data are superimposed is obtained. The amount of reflected light RL2 (a) from the second recording layer 2 to PD9 (a) and the amount of reflected light RL2 (b) to PD (b) are the same as those in the region X2.

  By removing the high-band component by the LPF 11, the differential signal LOD that is the output signal of the LPF 11 has a signal waveform proportional to (RL1 (a) + RL2 (a)) − ((RL1 (b) + RL2 (b)). Further, by removing the high-band component by the LPF 12, the addition signal LOA that is an output signal of the LPF 12 is proportional to (RL1 (a) + RL2 (a)) + ((RL1 (b) + RL2 (b)). In other words, the sum signal LOA, which is the output signal of the LPF 12, is further reduced, and the amplitude of the tracking error signal TE is increased in inverse proportion thereto, and the second recording layer 2 to the PD 9 (a). The offset amount generated in the tracking error signal TE due to the unevenness of the amount of reflected light to the PD 9 (b) is also larger than that in the region X2.

(Region X4)
The amount of reflected light RL1 (a) and RL1 (b) from the first recording layer 1 to the two-divided PD 9 is the same as that in the region X3, and the amount of reflected light RL2 (a) from the second recording layer 2 to the two-divided PD 9 , RL2 (b) are the same as those in the region X1. As a result, the difference signal LOD is the same as that in the region X1, and the addition signal LOA is larger than that in the region X3. As shown in the drawing, an amplitude change and an offset occur in the tracking error signal TE.

  As described above, in a conventional optical information recording / reproducing apparatus, in a multilayer recording medium having a plurality of recording layers, depending on the recording state of the recording layer other than the target recording layer for recording and reproducing information, The tracking error signal TE changes in amplitude and offset, the tracking servo signal amplitude also fluctuates, and the servo operation becomes unstable.

  Note that the focus error signal indicating the displacement of the recording surface and the focus of the light beam spot in the vertical direction of the disc also causes amplitude fluctuations and offsets due to the recording state of the other layers, and the focus servo becomes unstable as well as the tracking servo. .

  The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the amplitude and offset fluctuation of the tracking error signal with respect to the target recording layer of the multilayer recording medium and realize a stable tracking control operation. An object is to provide an optical information recording / reproducing apparatus.

  In order to achieve the above object, an optical information recording / reproducing apparatus according to the present invention includes a multilayer recording medium having a plurality of recording layers for recording or reproducing information along an information track, and an objective lens. An optical pickup that irradiates the recording layer with a light spot and detects the amount of reflected light from the recording layer of the multilayer recording medium, and based on the amount of reflected light detected by the optical pickup, the light spot and the information track in the disk radial direction Based on the amount of reflected light detected by the optical pickup and the tracking error detecting means for detecting the amount of positional deviation and outputting it as a tracking error signal, the recording layer on which the light spot is focused is recorded on the information track of the own layer. Based on the self-layer recording state detection means for detecting the recording state and the amount of reflected light detected by the optical pickup, the light spot is focused. Recording layer detection means for detecting the recording state of the recording layer other than the recording layer on the information track, and the recording state of the own layer and the other layer recording state detection detected by the recording layer detection means. The amplitude correction means for correcting the amplitude of the tracking error signal according to the recording state of the other layer detected by the means, the recording state of the own layer detected by the own layer recording state detection means, and the other layer recording state detection means According to the detected recording state of the other layer, an offset correction unit that corrects the offset of the tracking error signal is provided.

  In the optical information recording / reproducing apparatus according to the present invention, the other-layer recording state detecting means stores the reflected light amount detecting means for detecting the reflected light amount of the light spot from the multilayer recording medium, and the output signal of the reflected light amount detecting means. Reflected light quantity storage means, and the reflected light quantity when no information is recorded in other recording layers is stored in advance in the reflected light quantity storage means, and the output signal of the reflected light quantity storage means and the reflected light quantity detection means Based on the difference from the output signal, the recording state of the own layer and the other layer is discriminated.

  According to the present invention, it is possible to provide an optical information recording / reproducing apparatus that realizes a stable tracking control operation by reducing the amplitude and offset fluctuation of a tracking error signal with respect to a target recording layer of a multilayer recording medium.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration example of an optical information recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, parts having the same configurations and functions as those in FIG. 4 referred to in the description of the conventional example and the same signals are denoted by the same reference numerals and symbols, and description thereof is omitted.

  The present embodiment includes a self-layer recording state detection circuit 14, an other-layer recording state detection circuit 19, a TE amplitude detection circuit 23, a TE amplitude storage circuit 24, and an amplitude correction circuit 25 in addition to the configuration of the conventional example. An amplitude correction unit and an offset correction unit including a TE offset detection circuit 26, a TE offset storage circuit 27, and an offset correction circuit 28 are provided.

  In FIG. 1, the self-layer recording state detection circuit 14 receives the addition signal PDA of the output signals of PD9 (a) and PD9 (b) and extracts only a high-band signal component, and after passing through the HPF15. The recording signal amplitude detection circuit 16 for detecting the amplitude of the signal HO and the amplitude HOAD of the signal detected by the recording signal amplitude detection circuit 15 are stored, and the stored amplitude is multiplied by a predetermined coefficient (for example, 1/2). The magnitude relationship between the output signal HOAD of the first amplitude storage circuit 17, the output signal HOAD of the recording signal amplitude detection circuit 15 and the output signal Vth1 of the first amplitude storage circuit 17 is compared, and the comparison result is expressed as a signal CO1. And a comparator (COMP) 18 that outputs as follows.

  The other-layer recording state detection circuit 19 includes an addition signal amplitude detection circuit 20 for detecting the amplitude of the output signal LOA of the LPF 12, the amplitude LOAD of the addition signal detected by the addition signal amplitude detection circuit 20, and the output signal of the comparator 18. CO1 is stored as a set, the second amplitude storage circuit 21 outputs a signal Vth2 by performing a predetermined calculation (details will be described later) on the stored amplitude, and the output signal LOAD of the addition signal amplitude detection circuit 20 and the second The comparator (COMP) 22 compares the magnitude relationship with the output signal Vth2 of the second amplitude storage circuit 21 and outputs the comparison result as the signal CO2.

  The TE amplitude storage circuit 24 detects the amplitude TEAD of the tracking error signal TE detected by the TE amplitude detection circuit 23, and the own layer and other layers detected by the own layer recording state detection circuit 14 and the other layer recording state detection circuit 19, respectively. The recording state information CO1 and CO2 of the recording layer are stored as a pair, and after storing, the TE signal amplitude value corresponding to the recording state information CO1 and CO2 of the own layer and the other layers is read out and stored in the amplitude correction circuit 25 Output. The amplitude correction circuit 25 performs a predetermined operation (for example, dividing the tracking error signal TE by the output signal of the TE amplitude storage circuit 24) on the tracking error signal TE using the output signal of the TE amplitude storage circuit 24, and Output as tracking error signal TEca after amplitude correction.

  The TE offset storage circuit 27 calculates the offset amount of the tracking error signal TEOD detected by the TE offset detection circuit 26 in the own layer and other layers detected by the own layer recording state detection circuit 14 and the other layer recording state detection circuit 19. After being stored in combination with the recording state information, the TE signal offset amount corresponding to the recording state information of the own layer and the other layers is read and output to the offset correction circuit 28. The offset correction circuit 28 subtracts the output signal of the TE offset storage circuit 27 from the tracking error signal TEca after amplitude correction, and outputs the result as a tracking error signal TEco after offset correction.

  Next, the operation of the optical information recording / reproducing apparatus of the present embodiment configured as described above will be described with reference to FIGS. 2 and 3 in addition to FIG.

  2 and 3 show the optical information of the present embodiment shown in FIG. 1 when the position of the objective lens 8 with respect to the disc 3 is changed when information is reproduced from the first recording layer 1 of the disc 3. It is a wave form diagram of each part signal in a recording / reproducing apparatus. 2 and 3, the recording states (unrecorded or recorded) in the regions X1 to X4 are the same as the recording states of the respective regions shown in FIG.

  The tracking addition signal HO obtained by passing the addition signal PDA through the HPF 15 is a high frequency that is recorded data (change in light and darkness of high band) in the region X3 and the region X4 where the first recording layer 1 has been recorded. Extracted as a component. The recording signal amplitude detection circuit 16 detects the amplitude HOAD of the high-frequency component and stores it in the first amplitude storage circuit 17 in a region (X3 or X4) where the first recording layer 1 has been recorded in advance. After storing, a value half the stored amplitude is output as a signal Vth1 (indicated by a dotted line). The comparator 18 compares the output signal HOAD of the recording signal amplitude detection circuit 16 with the output signal Vth1 of the first amplitude storage circuit 17, and when the level of the output signal HOAD of the recording signal amplitude detection circuit 16 is high, the own layer Is output as a signal CO1.

  The addition signal amplitude detection circuit 20 detects the amplitude LOAD (indicated by a solid line) of the tracking addition signal LOA after passing through the LPF 12. The second amplitude storage circuit stores the output result of the addition signal amplitude detection circuit 20 in the areas X1, X2, X3, and X4 in advance, and the self-layer is not recorded (the self-layer recording state detection circuit 14). Output signal CO1 is low level), the average of the amplitude storage results in the regions X1 and X2 is recorded, and when the self-layer has been recorded (the output signal of the self-layer recording state detection circuit 14 is high level). The average of the amplitude storage results in the regions X3 and X4 is output as a signal Vth2 (indicated by a dotted line). After the storage, the comparator 22 compares the output signal LOAD of the addition signal amplitude detection circuit 20 with the output signal Vth2 of the second amplitude storage circuit 21, and the level of the output signal LOAD of the addition signal amplitude detection circuit 20 is small. In addition, a high level indicating that another layer has been recorded is output as a signal CO2.

  The TE amplitude detection circuit 23 detects the amplitude TEAD (FIG. 3) of the tracking error signal TE, and the TE amplitude storage circuit 24 detects each layer detected by the own layer recording state detection circuit 14 and the other layer recording state detection circuit 19. The recording state is stored in advance in combination with the recording state, and after the storage, the amplitude value corresponding to the recording state of each layer detected by the self-layer recording state detection circuit 14 and the other layer recording state detection circuit 19 is read, and the amplitude It is output to the correction circuit 25. The amplitude correction circuit 25 divides the tracking error signal TE by the output signal of the TE amplitude recording circuit 24 to obtain a tracking error signal TEca after amplitude correction shown in FIG.

  The TE offset detection circuit 26 detects the offset TEOD of the tracking error signal TEca after amplitude correction, and the detected offset TEOD is detected by the TE offset storage circuit 27 by the own layer recording state detection circuit 14 and the other layer recording state detection circuit 19. Is stored in advance in combination with the recording state of each layer detected by the above-mentioned, and after the storage, the offset value corresponding to the recording state of each layer detected by the self-layer recording state detection circuit 14 and the other layer recording state detection circuit 19 Is read out and output to the offset correction circuit 28. The offset correction circuit 28 subtracts the output signal of the TE offset storage circuit 27 from the tracking error signal TEca after amplitude correction, thereby obtaining the tracking error signal TEco after offset correction shown in FIG.

  In this way, a tracking error signal is obtained in which the tracking error signal amplitude in each region (X1 to X4) is kept constant and the tracking error signal offset is removed.

  As described above, according to the present embodiment, when reproducing information from a multi-layer recording medium composed of a plurality of recording layers, reflected light from not only the target recording layer but also an adjacent recording layer generates a tracking servo signal. Even if they enter a photodetector for detection and their offset changes depending on the recording state of the own layer and other layers, the amplitude and offset of the tracking error signal for each recording state of each layer are stored in advance. By detecting the recording state of the layer and other layers and correcting the tracking error signal according to the stored amplitude and offset, the amplitude and offset fluctuation of the tracking error signal are reduced, and stable tracking control operation is performed. Can be realized.

  The present invention is not limited to the above-described form. In the present embodiment, the description has been given focusing on the tracking error signal. However, the displacement in the disk vertical direction between the recording surface and the focal point of the light beam spot is described. The amplitude and offset of the focus error signal to be expressed varies depending on the recording state of the other layer and the own layer. However, with the same configuration as the present invention, the variation of the amplitude and offset of the focus error signal is reduced, and stable focus control operation is performed. Can be realized.

  In addition, in order to determine the recording state of the own layer and the other layer, the detection signal from the optical pickup is used, but information for specifying the area where information is recorded on the recording layer on the disc is specified. Recording area information means for writing as recording area information and optical pickup position detecting means for detecting the position of the optical pickup are provided, and the other layer and the own layer are recorded at the position detected by the recording area information and the optical pickup position detecting means. The same effect can be obtained even in a configuration for determining whether or not. Further, by using both methods in combination, it is possible to determine the recording state of the own layer and the other layer with higher accuracy.

  In this embodiment, the recording layer on the disc is described as two layers. However, when there are three or more recording layers on the disc, a plurality of other layer recording state detection means are provided to store each recording circuit. The same effect can be obtained by using a plurality of combinations of states.

  The optical information recording / reproducing apparatus according to the present invention has the advantage that the tracking error signal amplitude and offset variation with respect to the target recording layer of the multilayer recording medium can be reduced, and a stable tracking control operation can be realized. It is useful as an optical disc apparatus using another layer recording medium.

1 is a block diagram showing a configuration example of an optical information recording / reproducing apparatus according to an embodiment of the present invention. FIG. 1 is a waveform diagram of signals at various parts in the optical information recording / reproducing apparatus shown in FIG. 1 when the position of the objective lens 8 with respect to the disk 3 is changed when information is reproduced from the first recording layer 1 of the disk 3. When the information is reproduced from the first recording layer 1 of the disk 3, the signal of each part in the optical information recording / reproducing apparatus of the present embodiment shown in FIG. 1 when the position of the objective lens 8 with respect to the disk 3 is changed is changed. Waveform diagram A block diagram showing an example of the configuration of a conventional optical information recording / reproducing apparatus 4 is a waveform diagram of signals at various parts in the conventional optical information recording / reproducing apparatus shown in FIG. 4 when the position of the objective lens 8 with respect to the disk 3 is changed when information is reproduced from the first recording layer 1 of the disk 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st recording layer 2 2nd recording layer 3 Disc (multilayer recording medium)
4 Optical pickup 5 Semiconductor laser 6 Collimator lens 7 Beam splitter 8 Objective lens 9 (a), 9 (b) 2 split PD
10 Tracking error detection circuit 11, 12 LPF
13 Division circuit 14 Self-layer recording state detection circuit 15 HPF
16 Recording Signal Amplitude Detection Circuit 17 First Amplitude Storage Circuit 18, 22 Comparator 19 Other Layer Recording State Detection Circuit 20 Addition Signal Amplitude Detection Circuit 21 Second Amplitude Storage Circuit 23 TE Amplitude Detection Circuit (Amplitude Correction Unit)
24 TE amplitude memory circuit (amplitude correction means)
25 Amplitude correction circuit (amplitude correction means)
26 TE offset detection circuit (offset correction means)
27 TE offset storage circuit (offset correction means)
28 Offset correction circuit (offset correction means)

Claims (2)

A multilayer recording medium having a plurality of recording layers for recording or reproducing information along an information track;
An optical pickup that includes an objective lens, irradiates the recording layer of the multilayer recording medium with a light spot, and detects the amount of reflected light from the recording layer of the multilayer recording medium;
Tracking error detection means for detecting a positional deviation amount of the optical spot and the information track in the disk radial direction based on the amount of reflected light detected by the optical pickup, and outputting as a tracking error signal;
Based on the amount of reflected light detected by the optical pickup, a self-layer recording state detection means for detecting a recording state of the self-layer on the information track, which is a recording layer on which the light spot is focused,
Based on the amount of reflected light detected by the optical pickup, other layer recording state detection means for detecting a recording state on an information track of another layer which is a recording layer other than the recording layer on which the light spot is focused,
Amplitude correction means for correcting the amplitude of the tracking error signal according to the recording state of the own layer detected by the own layer recording state detection means and the recording state of the other layer detected by the other layer recording state detection means; ,
An offset correction unit that corrects an offset of the tracking error signal according to a recording state of the own layer detected by the own layer recording state detection unit and a recording state of the other layer detected by the other layer recording state detection unit; An optical information recording / reproducing apparatus. The other layer recording state detection means includes
A reflected light amount detecting means for detecting a reflected light amount of the light spot from the disk;
A reflected light amount storage means for storing an output signal of the reflected light amount detection means,
Based on the difference between the output signal of the reflected light amount storage means and the output signal of the reflected light amount detection means, the reflected light amount when no information is recorded in other recording layers is stored in the reflected light amount storage means in advance. The optical information recording / reproducing apparatus according to claim 1, wherein the recording state of the own layer and the other layer is discriminated.

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